Systems, methods, devices and device kits for fixation of bones and spinal vertebrae

ABSTRACT

Featured are a methods, systems, apparatus, and devices for fixing adjacent bone segments, segments of a bony structure and adjacent vertebrate of a spine utilizing an implant member as well as device kits related thereto. The methods, apparatuses and devices utilize an apparatus to forming a channel or aperture in or within the bone or bony structure segments or adjacent vertebra. In more particular embodiments such apparatuses and methods including forming an arcuate channel or aperture and which channel can receive therein a curved rod or implant member, which also preferably is arcuate, and avoids the associated problems with prior cage or straight rod and screw systems.

[0001] This application claims the benefit of U.S. ProvisionalApplication Serial No. 60/133,356 filed May 10, 1999, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention generally relates to methods, systems andapparatuses for bony fixation and more particularly to methods, systemsand apparatuses adapted for fixing the bones of the spine.

[0004] 2. Background of the Invention.

[0005] Fixation or fusion of vertebral columns with bone or material,rods or plates is a common, long practiced surgical method for treatinga variety of conditions. Many of the existing procedures involve the useof components that protrude outwardly, which may contact and damage abody part, such as the aorta, the vena cava, the sympathetic nerves, thelungs; the esophagus, the intestine and the ureter. Also, manyconstructions involve components that may loosen and cause undesirableproblems, often necessitating further surgical intervention.Additionally, limiting the success of these procedures are thebio-mechanical features of the spine itself, whose structure mustsimultaneously provide support to regions of the body, protect thevertebral nervous system and permit motion in multiple planes.

[0006] As indicated above, spinal surgery for spine fusion generallyinvolves using implants and instrumentation to provide support to theaffected area of the spine while allowing the bones thereof to fuse. Thetechnology initially evolved using bond chips around and on top of anarea of the Spine that had been roughened to, simulate a fracture in itsconsistency. The area, having encountered the bone chips, would thenproceed to heal like a fracture, incorporating the bone chips. However,surgical procedures dealing with the spine present notable challenges.For example, bioengineers have been required to identify the variouselements of the complex motions that the spine performs, and thecomponents of the complex forces it bears. This complexity has made itdifficult to achieve adequate stability and effective healing insurgical procedures directed to the spine.

[0007] One surgical technique provided by Cloward, involves cutting adowel type hole with a saw across or through the moveable intervertebraldisc and replacing it with a bone graft that was harvested from the hipbone. This procedure limits motion and mobility and results in a fusionof the adjacent vertebral bodies. However, as a result of the complexmotions of the spine, it is often difficult to secure the dowel fromdisplacing. Further, it has become apparent over time, however, thatthis particular technique does not always yield a secure fusion.

[0008] Other techniques have been developed that involve the placementof various hardware elements, including rods and hooks, rods and screwsand plates and screws. The dowel technique also has advanced over thepast five years or so, with dowels being fabricated from cadaver boneor, metals such as titanium or stainless steel. These techniques,whether using hardware, dowels or some combination thereof, have acommon goal to enhance stability by diminishing movement, therebyresulting in or enhancing the potential of a fusion of adjacentvertebral bones. For example, in one of these other techniques, the discis removed and adjacent vertebrae are positioned in a stable position byplacing a plate against and traversing them, which plate is secured oranchored to each by means of screws.

[0009] In another procedure, cages in the form of two parallel circularor rectangular devices are made out of a material such as titanium orstainless steel and these devices are fenestrated. Bone is packed in thecenter of the devices that will heal to adjacent bone through eachfenestration. In this procedure, the disc space is distracted so allligamentous structures are taut and the bones are held in their normalmaximal position of distraction. Because the cages are implanted inspongy bone, they are more likely to collapse the surrounding bone, thusresulting in loss of distraction and subsequently cage dislodgment.

[0010] U.S. Pat. No. 5,591,235 reports a certain spinal fixation deviceand technique for stabilizing vertebrae. In this technique, a hollowscrew is inserted into a hole, preferably a hole saw recess, in eachadjoining vertebrae. A channel is cut into the vertebrae, which is linedup with corresponding axial slots in the screw. A rod is inserted intothe channel and so as to pass through the axial slots in the screw. Therod is secured to each of the screws by means of a locking cap. The rodalso is arranged so as to provide a bridge between the hollow screws inthe adjoining vertebrae. Certain disadvantages have been surmised usingsuch a device and technique. For example, it has become apparent thatthe trough in the vertebral bodies destabilizes some of the cortex ofthe vertebrae body wall, which is the strongest component.

[0011] Thus, it would be desirable to provide a new apparatus, systemand methods for spinal fixation that enhances healing of the bone whileproviding structural support to the spine. It would be particularlydesirable to provide such an apparatus, system and method that wouldinvolve the use of open surgical, or minimally invasive surgicaltechniques as well as a technique in which the implant burrows in thebone spine, traverses across the disk space, and ends in an adjacent orneighboring vertebrae or vertebras, providing limited or no protrusions.It also would be desirable to provide such an apparatus, system andmethod where the implant is retained within the bone without requiringcontour-varying external vertebral wall fixation as compared toconventional devices, as such a device would avoid many of the problemsassociated with conventional devices such as blood vessel injury,erosion into organs, as well as placement near nerves.

SUMMARY OF THE INVENTION

[0012] I have now found new methods and apparatus for fixing adjacentvertebrate of a spine. The methods and apparatus of the inventionutilize a new implant member, which preferably is arcuate, and avoidsthe associated problems with prior cage or straight rod and screwsystems. It is within the scope of the present invention for the implantmember to have any geometric shape or configuration consistent with theintended use including a straight member.

[0013] Preferred methods of the invention for stabilizing adjacentvertebrae of the spine, include the steps of providing a positioningapparatus including two guide sleeves, each guide sleeve having a longaxis and locating the two guide sleeves with respect to the adjacentvertebrae such that a vertex formed by the long axis of each guidesleeve is located in the intervertebral space for the adjacentvertebrae. The method further includes forming an aperture in each ofthe adjacent vertebrae using the guide sleeves and inserting an implantinto the apertures formed in each of the adjacent vertebrae so that theimplant extends between the adjacent vertebrae and through theintervertebral space.

[0014] Preferably, the aperture formed in the vertebrae is arcuate andthe implant being inserted also is arcuate. The arcuate aperture in eachvertebrate can be suitably formed by drilling or other ablation. Moreparticularly, an initial aperture can be drilled in each of the adjacentvertebrae to create intersecting apertures with convergent paths withinthe intervertebral space; and the initial aperture then enlarged toreceive the implant. That enlarging of the initial aperture can besuitably performed by a variety of procedures, e.g. by using a drillbit, a reamer, an awl, impaction drill, shape memory coring device, or,curved coring device, or the like.

[0015] The step of forming an aperture also can further includeinserting a guide member, after drilling of the initial aperture, intoone of the guide sleeves, down through the initial aperture in oneadjacent vertebrae, through the intervertebral space and into theinitial aperture in the other adjacent vertebrae; and advancing anaperture enlarging device over the guide member so as to enlarge theinitial aperture. In this case, the aperture enlarging device issuitably a curved reamer or a curved drill bit, and the curved reamer orthe curved drill bit is advanced over the guide member so as to form anarcuate aperture in each of the adjacent vertebrae. It also should beappreciated that multiple vertebral holes can be created using the samemethods as disclosed herein. In that manner, multiple arcuate implantscan be placed, e.g. if greater mechanical stability is considereddesirable.

[0016] The positioning apparatus can further include a cross member andan intervertebral spacer, preferably where the guide sleeves arepivotally mounted to the cross member and the intervertebral spacer isspaced from the cross member and interconnected thereto at about a midpoint between the pivot points for the guide sleeves. In this case, thestabilizing method can further include locating the intervertebralspacer in the intervertebral space between the adjacent vertebrae; andmaintaining alignment of the guide sleeves with respect to the adjacentvertebrae so that a consistent angle is maintained between the guidesleeve and the vertebrae during at least a portion of said forming ofthe aperture. The intervertebral spacer also can be configured so as toprovide, protection to the spine during the drilling when disposed inthe intervertebral space.

[0017] In an alternative embodiment, the positioning system beingprovided includes a cutter bracket system and a curved drillingsub-system affixed thereto. The cutter bracket system includes a pivotarm whose pivot point is disposed between the adjacent vertebraeopposite the intervertebral space. More particularly, the pivot point isat about the midpoint between the adjacent vertebrae. The curveddrilling sub-system is affixed to the pivot arm such that as the pivotarm rotates about the pivot point the curved drill sub-system follows anestablished cutting path. In a more specific embodiment, the drillingsub-system is affixed proximal or at the distal end of the pivot arm.The positioning apparatus according to the alternative embodiment canfurther include a mechanism that temporarily secures the cutter bracketsystem to the adjacent vertebra to be fused and which positions andmaintains the pivot point at the desired location. Also, the curveddrill subsystem can include a curved cannula, a flexible member runningthrough the curved cannula and a cutting burr secured to an end of theflexible member.

[0018] As, to the step of forming an aperture using a positioning systemaccording to the alternative embodiment, this step includes rotating thepivot arm in one direction about the pivot point so the curved drillingsub-system forms an aperture in one of the adjacent vertebrae androtating the pivot arm in another direction about the pivot point so asto form an aperture in the other of the adjacent vertebrae. Ina morespecific embodiment, the step of forming further includes remounting thecurved drilling sub-system to the pivot arm before rotating the pivotarm in the another direction so a cutting element of the curved drillingsubsystem is aligned for the direction of movement.

[0019] As to inserting the implant, the method step includessuccessively drawing a portion of the implant through the arcuateaperture in one adjacent vertebrae, through the intervertebral space andinto the arcuate aperture of the other adjacent vertebrae. In a specificembodiment, the step of inserting includes securing one end of a guidewire to an end of the implant; passing, a free end of the guide wirethrough the arcuate aperture in one of the adjacent vertebrae throughthe intravertebral space and through the arcuate aperture in the otheradjacent vertebrae, and pulling on the guide wire free end to therebysuccessively draw the portion of the implant.

[0020] In another embodiment, the step of inserting includes inserting abeginning end of the implant into an entrance opening of one of theadjacent vertebrae; applying a force to the portion of the implantextending from the entrance opening so as to drive the implant beginningend though the arcuate aperture in the aperture of said one of theadjacent vertebrae, through the intervertebral space and into thearcuate aperture in the other of the adjacent vertebrae.

[0021] The implant being inserted into the final aperture is made fromone or more of a metal (e.g., titanium or stainless steel), bone,morphogenic protein (including a combination of bone and bonemorphogenic protein), carbon fiber composite, nitinol or biodegradablematerials such as polyactic acid or polyglycolic acids and copolymersand other derivatives thereof, or collagen and collagen coated metal orbone. The implant also may comprise an in situ-formed plug where theaperture acts as a mold for an epoxy or other polymer-based system.Also, the implant can be solid or hollow and arranged with or withoutingrowth fenestrations and screw holes for post-insertion securement.The implant also can be configured so the implant includes a first and asecond section, where a distal end of each, of the first and secondsections is configured so as to be capable of being secured together.For such an implant, the method further includes the steps of insertingthe first section into the aperture in one of the adjacent vertebrae sothat the distal end therefore is disposed in the intervertebral space;inserting the implant second section into the aperture in one of theadjacent vertebrae so that the distal end therefore is disposed in theintervertebral space; and securing the distal ends of the first andsecond sections together. The implant sections being inserted can bearcuate with a radius substantially the same as the arcuate aperture orsubstantially straight. In particular embodiments, the distal ends ofthe implant sections are secured to each other by e.g. a nut, bolt, pin,expansion or press-fit device, or interlocking member on the end of eachsection. Other stabilization methods also can be employed. For instance,a plate can be applied to the vertebrae surface with attachments at eachend of the tunnel traversed by an implant in accordance with theinvention.

[0022] Another method of the present invention for stabilizing adjacent,vertebrae of the spine includes the step of forming a common channel inand between the adjacent vertebrae and inserting a biscuit implant inthe common channel so as to bridge between the adjacent vertebrae. Inmore specific embodiments, the step of forming includes simultaneouslycutting a slot, preferably an arcuate slot, in each of the adjacentvertebrae so as to form the common channel and providing a deviceconfigured so as to be capable of simultaneously cutting the slot ineach, of the adjacent vertebrae. Also for said step of inserting, thebiscuit implant can be further configured so as to include a spacerelement that is received in the intervertebral space between theadjacent vertebrae when the biscuit is disposed in the common channel.

[0023] In another alternative aspect of the invention, a diskectomy canbe performed and a stabilizing wedge (inner) implant inserted betweenthe vertebrae. The wedge (inner tool) establishes lordosis, provides aconstruction reference, and carries on it the stabilizing wedge implant.Retracted stop-cut blades on the inner tool are then engaged, cuttinginto the vertebrae in the vertical plane. A hole saw cane be used tocreate a circular cut in the vertebrae to facilitate insertion of theouter implant. Once the cut is complete, the bone harvested in thetubular cutter can be manipulated into the implant. A circular (outer)implant is then inserted over the inner tool. The outer tool thenreferences the position of the inner tool and guides the implant intoplace. After the two implants nest together along a key and groove, theouter tool is re moved. A fenestrated circular member then replaces theouter cutting tool and the inner tool is rotated about 90 degrees andthen removed. Working together, the two rotated implants capture thevertebral body sections, which are now rotated about 90 degrees andthrough their many holes, provide blood exchange with the adjacent boneto accomplish fusion.

[0024] Also featured is a system and apparatus embodying the describedmethods or techniques for internal fixation of the spine.

[0025] Other aspects and embodiments of the invention are discussedbelow.

BRIEF DESCRIPTION OF THE DRAWING

[0026]FIG. 1A is a schematic view of a positioning jig according to thepresent invention;

[0027]FIG. 1B is a front view of the intervertebral spacing member ofFIG. 1A;

[0028]FIG. 2A is a schematic view of the positioning jig of FIG. 1Adisposed about two vertebral bodies;

[0029]FIG. 2B is a schematic view of an alternative positioning jigaccording to the present invention disposed about two vertebral bodies;

[0030] FIGS. 3A-E are schematic views that illustrate the various stepsof the process to form a hole in each vertebral body for implanting afixating member therein;

[0031]FIGS. 4A and 4B are schematic views that illustrate alternate waysof making a hole in each vertebral body;

[0032]FIG. 4C is a plan view of a Romano device for making a curvedhole. Shown is one of the two opposed curved cutter guides and aflexible cable having a cutting bit attached to one end;

[0033]FIG. 5A is a schematic view of one device for implanting thefixating member;

[0034]FIG. 5B is a schematic view of alternate device for implanting thefixating member;

[0035]FIG. 6A is a schematic view of the vertebral bodies illustratingthe implantation of the fixating member in the holes;

[0036]FIG. 6B is a schematic view of the vertebral bodies to illustratesecuring of the fixating member;

[0037] FIGS. 7A-C are schematic views of the implantation of a fixatingmember made from nitinol;

[0038] FIGS. 8A-B are exemplary cross sectional views of a guide sleeveincluding a mechanical guide to guide the nitinol fixating member duringinsertion;

[0039]FIG. 9 is a schematic view of the vertebral bodies with a fixatingmember according to a second aspect of the present invention;

[0040]FIG. 10 is a schematic view of the vertebral bodies with afixating member according to a third aspect of the present invention;

[0041]FIG. 11A is a schematic view of a cutter bracket system accordingto the present invention;

[0042]FIG. 11B is a schematic view of a curved drill used with thecutter bracket system of FIG. 11A;

[0043]FIG. 12A is a perspective view of a common channel cutting deviceaccording to the present invention;

[0044]FIG. 12B is a perspective view of a portion of the channel cuttingdevice of FIG. 12A with the cutting implement extended;

[0045]FIG. 12C is a schematic view of the channel cutting device of FIG.12A disposed on two vertebral bodies;

[0046]FIG. 12D is a schematic view of the two vertebral bodies toillustrate the implantation of the biscuit implant in the cut commonchannel;

[0047]FIG. 12E is another view: of the two vertebral bodies toillustrate the implantation of the biscuit implant including a spacingelement in the cut common channel

[0048]FIG. 12F is a perspective view of the biscuit implant of FIG. 12D;

[0049]FIG. 12G is a side view of the biscuit implant with spacingelement of FIG. 12E;

[0050] FIGS. 12H-K are perspective views of various exemplary biscuitimplants according to the present invention;

[0051] FIGS. 13A-13F illustrate an alternative implant system of theinvention; where FIG. 13A is an isometric view of an inner implant, FIG.13B is an isometric view of an outer implant, FIG. 13C is a lateral viewshowing a preferred positioning of the implant system, FIG. 13D is ananterior view of the outer implant within which the inner implant issecured, FIG. 13F is an anterior view of the outer and inner implantafter rotation, and FIG. 13F is a perspective view of an embodiment ofthe implant system;

[0052]FIG. 14A is a schematic view of an inner tool positioned withinthe intervertebral disk space;

[0053]FIG. 14B is an isomeric view of the inner tool;

[0054]FIG. 14C is a cross-sectional view of the inner tool, withretracted and extended stop-cut blades;

[0055]FIG. 15 is a schematic view of the inner and outer tool systempositioned in relation to the vertebral bodies; and

[0056]FIG. 16 is a schematic view showing bone-to-bone with no gapapplication.

DETAILED DESCRIPTION OF THE INVENTION

[0057] Referring now to the various figures of the drawing wherein likereference characters refer to like parts, there is shown in FIGS. 1-2various schematic views of a 10 drill guide or positioning jig 100 thatpositions or aligns the drill bits before making the holes in each ofthe vertebral bodies 2. The positioning jig 100 includes two guidesleeves 102, a cross member 104 and an intervertebral spacing member110. Each guide sleeve 102 preferably is a hollow tubular member havinga lumen or passage therein for receiving and guiding the means forforming at least the initial aperture in the adjacent vertebrae such asa drill bit 150 (FIG. 3B). As indicated elsewhere herein, the aperturemay be formed using other techniques such as the ablation of bone by anenergy source, e.g., high-pressure water, high-pressure air, ultrasound,or a laser. As such, it shall be understood that the internal sizing andconfiguration of the guide sleeves is established to accommodate theparticular mechanism used for forming the aperture.

[0058] The guide sleeves 102 are mounted to the cross member 104 in sucha way that they are each pivotal about the cross member and so each canbe secured or locked in a particular angular position with respect tothe cross member. Although a single mounting/pivot point 106 isillustrated, it is within the scope of the present invention for thecross member 104 and each guide sleeve 102 to be configured with aplurality or more of such pivot/mounting points. In an exemplaryembodiment, the cross member 104 and guide sleeves 102 are constructedfrom stainless steel; and each guide, sleeve is pivotally secured to thecross member by screws.

[0059] The distal end 108 of each guide sleeve 102 is configured formechanically engaging a surface, edge, comer or other surface artifactor feature of the vertebral body. 2. In an exemplary embodiment and asmore clearly illustrated in FIG. 3A, the guide sleeve distal end 108 isconfigured or arranged with a cutout that is designed to accept thecorner of the vertebral body 2. Additionally, the cutout area and thusthe distal end 108 also are configured with a plurality or more of teeth107. The teeth 107 are configured and arranged so the teeth bite intothe bony surface of the vertebral body when the comer of the vertebralbody 2 is received within the cutout area of the guide sleeve distal end108. Each guide sleeve is suitable about 20 cm in length, althoughsuitable and preferred guide sleeve length s can vary-depending on themethod of access.

[0060] The intervertebral spacing member 110 includes an intervertebralspacer 112 and an interconnecting member, 114 that mechanicallyinterconnects the cross member 104 and the intervertebral spacer 112.The interconnecting member 114 is secured to or, retained by the crossmember 104 so as to be maintained in fixed relation with respect to thepivots 106 for both guide sleeves 102. In an exemplary embodiment, theinterconnecting member 114 is located at about the midpoint of the crossmember 104 between the pivots 106. The interconnecting member 114 alsois secured to the cross member 104 so the intervertebral spacer 112 ispositioned between the distal ends 108 of the guide sleeves 102. Moreparticularly, the interconnecting member 114 is positioned so theintervertebral spacer 112 is received within the distended disc spacebetween the adjacent vertebral bodies 2.

[0061] In an exemplary embodiment, the interconnecting member 114 is inthe form of a rod and the cross member 104 is configured with a throughaperture 109 in which the rod is received. This configuration provides amechanism by which the interconnecting member 114 is put into andmaintained in fixed relation with respect to the pivot points 106. It iswithin the scope of the present invention for the cross member 104 tohave any geometric shape, as well as being hollow or solid inconstruction, that is otherwise consistent for the intended use of thepositioning jig 100.

[0062] The interconnecting member 114 also can be configured so as toprevent rotational motion of the interconnecting member with respect tothe through aperture 109. For example, the rod and through aperture 109may be configured so as to include a flat side in a portion of thecircumference for the through aperture and the rod. Alternatively, thethrough aperture and rod maybe arranged; with a key and notcharrangement to prevent rotation.

[0063] When the guide sleeves 102 are secured to the cross member 104and each guide sleeve distal end 108 mechanically engages the surface ofthe, vertebral body 2, the guide sleeves are arranged so they maintain aconsistent angle with respect to the vertebral body. Additionally, andin combination with the intervertebral spacer 112, this arrangementprovides a three-point reference that ensures appropriate angles, andalignment are maintained. Additionally, such a configuration establishesa condition whereby the positioning jig 100 locks down on the motionsegment of the spine to be stabilized.

[0064] The use of the positioning jig 100 in the method of the presentinvention can be understood from the following discussion with referenceto FIGS. 1-6. It shall be understood that as preparation for spinalfixation/stabilization the medical personnel (e.g., surgeon) obtainsaccess to the motion segment or structures to be stabilized or fusedusing any of a number medical/surgical procedures known to those skilledin the art. In this regard, this would involve such actions as preparingthe disc space and performing retraction of vessels, muscles and nerves.

[0065] In this regard, it should be recognized that the method andpositioning jig 100 of the present invention are particularlyadvantageous when performing a minimally invasive surgical procedure.The minimally invasive procedure can be performed through three holes,each about 1 inch across, in the abdomen and allows for the procedure tobe executed without visualizing the vertebrae. Thus, and in contrast toa number of prior procedures, methods of the invention are not limitedto an anterior presentation. Such methods of the invention also can beperformed through a posterior, posteriolateral or pedicular approach.

[0066] In addition, when using a nitinol implant, the positioning jig100 allows the implant to be properly positioned for and duringinsertion thereof. After gaining access, the surgeon also could scrapeout the material from the failed disc or use this disc or its space as areference point.

[0067] As preparation, the surgical personnel also select anintervertebral spacing member 110 that is appropriately sized so it canaccommodate the distended disc space. The intervertebral spacer 112portion of the intervertebral spacing member 110 is inserted into theintervertebral space 4 between the adjacent vertebrae. In this way, theapproximate center or mind point of, and the staring point on, theadjacent vertebrae to be fused or stabilized is thereby established, ordefined.

[0068] The intervertebral spacer allows the surgeon to maintainextremely accurate disk spacing. The intervertebral spacer also protectsthe spinal cord from accidental drilling or boring. If desired, thespacer can be made of bone and can be made with or without a throughhole. The spacer design is suitably based on a construction thatfacilitates the selected technique for creating an arcuate aperture. Anintervertebral spacer that is comprised of bone offers the advantage ofbeing able to remain implanted following the procedure.

[0069] Other materials also can be suitably employed to form anintervertebral spacer. The placement of an implant provides a centralaxis through which a compressible, functional intervertebral disk membercan be reliably secured. The artificial disk member suitably can be madefrom a variety of compressible materials, including e.g. silicon,elastomeric polymers, polyurethanes and copolymers thereof, hydrogels,collagen or bioabsorbables.

[0070] Next, the positioning jig 100 is locked down on top of the motionsegment to be immobilized, as more clearly shown in FIG. 2. In thisregard, the surgical personnel slide the interconnecting member 114 ofthe intervertebral spacing member 110 into an aperture 109 provided inthe cross member 104. In this way, the aperture 109 in the cross member104 positions the intervertebral spacing member 110 between the distaland proximal ends of the drilling guides 102. Although illustrated asbeing located in the mid-point, the intervertebral spacing member can becentrally located or offset to either side to enable drilling of holesin the vertebrae laterally against the spine.

[0071] Preferably, the aperture 109 in the cross member 104 isconfigured so as to prevent the cross member 104 or intervertebralspacing member 110 from rotating with respect to each other. Forexample, a portion of the aperture 109 and a portion of theinterconnecting member 114 is flattened so as to predefine a givenorientation. Alternatively, the aperture 109 is configured with a notchor keyway and the interconnecting member 114 is configured with a key orprotrusion that is received in the keyway.

[0072] As provided above, the distal end 108 of each guide sleeve 102 ispreferably configured so each distal end mechanically engages thesurface of the vertebrae 2. In the illustrated embodiment, the distalend 108 is arranged with a cutout area that is designed to accept thecorner of the vertebrae 2 as more clearly illustrated in FIG. 3. As alsoshown in FIG. 3, the cutout area is provided with a plurality of teeth107 that bite into the bony surface of the vertebrae 2. It is within thescope of the present invention for the guide sleeve distal end 108 to bedisposed at other positions on the surface of the vertebrae 2 such asthat illustrated in FIG. 6A.

[0073] After locating the positioning jig 100 with respect to the motionsegment to be fused, the surgical personnel secure the guide sleeves 102at each of the pivots 106. This advantageously ensures that theappropriate angles and, alignment of the guide sleeves 102 with respectto the vertebrae 2 are maintained as well as locking the positioning jig100 down on the motion segment to be fused.

[0074] As noted above, an initial through hole is formed in eachvertebrae 2 by any of a number of methods, e.g. by a drill, by ablationof the material comprising the vertebrae using an energy source such asRF, ultrasonic waves, cryogenics and water jets or by any other as knownto those skilled in the art and which can be adapted for use with thepositioning jig 100 of the present invention. For purposes of describingthe present invention however the following discussion is simplified todescribing the terms of drilling the initial aperture or initial throughhole 6 in the vertebrae 2. This, however, shall not be inferred as beinga limitation on the method according to the present invention to onlydrilling.

[0075] A fixed or flexible drill bit 150 is inserted into and down eachdrill guide 102 so the ends thereof contact the surface of the vertebrae2. The surgical personnel operate the drill bits in accordance withaccepted techniques so as to create an initial through hole 6 in each ofthe vertebrae. Preferably, and as shown in FIG. 3B, the through holes 6being created are intersecting with convergent paths within theintervertebral space 4. In other words, the projection of the long axisfor each of these through holes 6 intersects so the vertex created byintersection of the long axes is located within the intervertebral space4.

[0076] The initial through hole 6 initially formed in each vertebrae 2has a diameter much less than that of the implant 160 that is to be usedto stabilize or fuse the motion segment. After forming the initialthrough hole 6, the surgical personnel insert a guide wire 170, such asa 0.093 inch nitinol guide wire, into and down one guide sleeve 102 andthrough the through hole in one vertebrae 2. The surgical personnelcontinue to push the guide wire 170 across the intervertebral space 4and into the through hole 6 in the other vertebrae as more clearlyillustrated in FIGS. 3C-D. In a particular, embodiment the guide wire170 is configured with a slightly curved tip. The guide wire 170 isgenerally in a curved configuration when disposed in the through hole 6of the vertebrae 2.

[0077] A flexible/curved drill bit 152 is then passed through one of theguide sleeves 102 and over the, guide wire 170 so as to form a curvedthrough aperture 6 a in each of the vertebrae as shown in FIG. 3E. Thecurved or arcuate through aperture 6 a is formed with a cross-sectionthat complements the cross-sectional shape of the implant 160.Preferably, the arcuate through aperture is sized to be slightly smallerthan that of the implant 160 so there is a friction; snug orinterference fit between the implant 160 and the arcuate throughaperture 6 a.

[0078] In this way, when the implant 160 is inserted into the arcuatethrough aperture 6 a, it will remain therein without further need ofscrews or other artifacts or devices for securing the ends of theimplant to each vertebrae 2. It is within the scope of the presentinvention, however, for screws or other devices be provided as anadditional measure or protection for securing the implant 160 within thevertebrae 2.

[0079] Alternatively, the curved or arcuate through aperture 6 a isformed using any of a number of other techniques as described below. Inone case, and as shown in FIG. 4A, the arcuate through aperture 6 a isformed in the vertebrae 2 by using a flexible reamer 200. The flexiblereamer is run or passed over the guide wire 170 to ream or core out thearcuate through aperture 6 a. The cancellous bone of the vertebrae 2 isrelatively soft so that it is possible to use a reamer to core the holeaperture. Similarly, and as shown in FIG. 4B, a curved awl or aprogressively larger guide wire 170 a can be used to punch a curved holein the vertebrae. FIG. 4C shows a Romano device suitable for drilling acurved bore such as that disclosed in U.S. Pat. No. 5,700,265 theteachings of which are incorporated herein by reference. A swing arm 830and curved guide arm 834 navigate the drill bit 840 through a definedradius of curvature.

[0080] In addition to the mechanical devices for drilling, punching orreaming out the arcuate through aperture 6 a, the discharge end of anenergy source, such as RF, ultrasonic, cryogenics laser and water, canbe located within the guide sleeve 102 and passed over the guide wire soas to form the arcuate through aperture. For example, the nozzle(s) of ahigh pressure water source can be arranged so the discharging or icecrystal water impinges on the bony material of the vertebrae 2 and thematerial is thereby ablated away to form the arcuate through aperture 6a. Similarly, laser light, RF waves or ultrasonic waves can be focusedon the bony material within the vertebrae 2 to form the arcuate throughaperture 6 a.

[0081] The foregoing describes the formation of the arcuate throughaperture 6 a that receives the implant 160 by passing a mechanism fromthe entrance to the exit of the initially formed through hole 6. It iswithin the scope of the present invention, for a guide to be locatedwithin the intervertebral space 4 so the curved through aperture isformed by drilling from the intervertebral space out, rather from theoutside in.

[0082] There is shown in FIG. 2B a schematic view of an alternativepositioning jig 100 a that is disposed about two vertebral bodies. Thisalternative positioning jig 100 a is similar to the positioning jig 100of FIG. 2A except for the guide sleeves. As such reference shall be madeto the foregoing discussion regarding FIGS. 1-2A for further details asto the common features for these two positioning jigs 100,100 a. In theeillustrated embodiments, a guide wire 170 is being inserted into one ofthe guide sleeves 102 a and 4 is configured so that the proximal end ofthe guide wire 170 is arranged so as to include an impact fitting toprotect the guide wire about the proximal end.

[0083] In the alternative embodiment, the guide sleeves 102 a aretubular members that are configured so that at least a portion 103 ofeach guide sleeve is arcuate. In the illustrated embodiment, the arcuateportion 103 of the guide sleeve 102 a is proximal the vertebral bodysuch that one end of the arcuate portion comprises the distal end 108 ofthe guide sleeve that is in contact with the vertebral body 2. It iscontemplated, however, that the guide sleeve can be configured so as tobe substantially arcuate between the vertebral body 2 and the crossmember 104.

[0084] The arcuate shape provides a convenient mechanism that cansimplify the above-described process for making an arcuate through hole6 a in the vertebral body 2. The arcuate shape also provides a mechanismto orient the tool, device or apparatus being inserted into the guidesleeves 102 a, for example the drill or high energy source for formingthe initial through hole, so use of the tool etc. is more convenient tothe surgical personnel performing the procedure.

[0085] After the arcuate through aperture 6 a is formed, then theimplant 160 is inserted therein so it is disposed within the throughaperture 6 a in one vertebrae 2, passes or extends across theintervertebral space 4 and disposed within the through aperture 6 a ofthe other vertebrae. The implant 160 is made from any one ore moresuitable materials such as e.g. a metal such as titanium or stainlesssteel, bone, bone with bone morphogenic protein, carbon fiber composite,nitinol. The implant being inserted into the final aperture is made fromone or more of a metal (e.g., titanium or stainless steel), bone,morphogenic protein (including a combination of bone and bonemorphogenic protein), carbon fiber composite, nitinol or biodegradablematerials such as polyactic acid or polyglycolic acids and copolymersand other derivatives thereof, or collagen and collagen coated metal orbone. The implant also may comprise an in situ-formed plug where theaperture acts as a mold for an epoxy or other polymer based system. Theimplant, preferably is curved so it generally conforms; to the radius ofthe arcuate through apertures 6 a in each vertebrae 2, however, othergeometric shapes are contemplated that are consistent with the intendeduse including straight members.

[0086] The implant 160 suitably can be provided with a circular or ovalshape. The diameter or width of the implant can vary over a relativelybroad range and may depend on the size of the vertebrae and desiredimplant stiffness. More specifically, in preferred embodiments, theimplant may suitably range in diameter or width from about 5 mm or assmall as is mechanically sufficient, to sizes approaching that of largeintramedullar rods, or about, 22 mm. Preferably the implant should havea diameter or width from about 7 to 12 mm, more preferably about 9 mm.The implant also preferably should have an appropriate radius ofcurvature such that both vertebrae are engaged while staying well clearof the spinal cord. That radius preferably is about 1.5 inches, asreferenced from the arcuate implant's inner radius.

[0087] The implant 160, is suitably a solid or hollow (e.g., tubular)member. The implant can be suitably configured so as to havefenestrations 166 (FIG. 6A) that allow biologic elements of bone totraverse through it or across it, thereby enhancing potential forstability and for cross-segmental healing. In particular, the implant160 can have cutting fenestrations similar to a cheese grater, allowingfragments of bone to be pared off as the implant 160 is being insertedinto the through apertures in either vertebrae. A fenestrated implant160 that is hollow can be filled with bone chips or synthetic orengineered bone healing materials, allowing for bone ingrowth, and acheese grater type of implant with cutting fenestrations can add freshlypared fragments of bone to the packed bone chips or other materials toenhance bony ingrowth. Additionally, the fenestrations, 166 can besurface dimples, sharpened edges, cutting indentations or otheralterations in the exterior surface of the implant 160: to enhance orfurther ensure the secure fitting of the implant into the arcuatethrough aperture 6 a as well as for facilitating bone growth.

[0088] The particular technique for inserting the implant 170 into thethrough aperture 6 a of a vertebrae 2 for fixing of the movable segmentis dependent upon the material used to make the implant. For an implant160 made from titanium, and as shown in FIG. 5A, a threaded end 162(e.g., a female threaded end) is provided at one end of the titaniumimplant 160 for threaded engagement with the threaded counterpart (e.g.,male counterpart) at one end 172, the distal end of the guide wire 170.This can be accomplished for example by removing at least one of theguide sleeves 102 from the entrance opening of one through aperture 6 aso the threaded end 172 of the guide wire is exposed. The implantthreaded end 162 is then screwed onto the guide wire threaded end 172and the so tethered end 162 of the implant 160 is positioned at theentrance opening of the through aperture 6 a and pulled into place bypulling on, for example, the proximal end 174 of the guide wire 170.

[0089] Preferably, the distal end 108 of one guide sleeve 102 remainsengaged at the entrance opening for the other through aperture 6 a, soas to serve as a bearing surface or brace for the guide wire 170 as itis being pulled out of this entrance opening. This is done to keep theguide wire 170 from cutting through the cantellous bone when the guidewire is under tension because of the pulling action. Alternatively, atubular member with a rounded surface may be advanced over the guidewire and through the remaining guide sleeve 102, to ensure that theguide wire pulls from the appropriate angle. This technique is suitablefor use with metallic and other rigid material type of implants.

[0090] Alternatively, and as shown in FIG. 5B, a pushing mechanism is,useable for inserting or tamping the implant 160 into the arcuatethrough apertures 6 a. In the illustrated embodiment, an arcuate pushingmechanism 300 is configured so as to rotate about an axis of rotationthat corresponds generally to the center of the circle subscribed by thearcuate through apertures 6 a. The arcuate pushing mechanism applies aforce to the distal end of the implant 160 so as to drive the proximalend of the implant through the arcuate through aperture 6 a in onevertebrae, across the intervertebral space 4 and into the arcuatethrough aperture 6 a of the other vertebrae 2.

[0091] In the illustrated embodiment; the positioning jig 100 is removedexcept for the intervertebral spacing member 110 or bone intervertebralspacer where the intervertebral spacer 114 remains disposed in theintervertebral space 4. The arcuate pushing mechanism 300 is attached tothe end of the interconnecting member 112 by means of a jig or othermember or device so the pushing mechanism can rotate about the end ofthe interconnecting member. In this way, the arcuate arm 302 of thepushing mechanism 300 can be advanced by having one of the surgicalpersonnel rotating it about its axis of rotation. Alternatively, or inaddition to the surgical personnel can strike one end 304 of the arm 302with a mallet or other weighted object so as to drive the implant 160into the through aperture 6 a. For example, striking may be requirednear the end of the insertion process when there is maximum frictionbeing developed on the inserted implant. The arm 302 also may beconfigured with a curved support sleeve 306 in which the implant isreceived.

[0092] Although the implant 160 and through apertures 6 a are sized sothat there is preferably at least a snug fit therebetween, as an extrameasure of protection, the implant 160 may be further secured in placeat its ends by means of screws 400 as shown in FIG. 6B. Alternatively,the implant 160 may be secured in place by a plate, screw, staple or acombination thereof. Additionally, the implant can be arranged so as toinclude a biting or expansion element(s) that can be driven out in alateral direction so as to engage the bony structure of the vertebrae 2.

[0093] As provided above, and as shown in FIGS. 7A-B, the implant 160 acan be made from nitinol. A nitinol implant 160 a is advantageous inthat a curved nitinol implant can be straightened as shown in FIG. 7Bprior to insertion into the arcuate through apertures 6 a. Thestraightened nitinol implant 160 a can be advanced down one of the guidesleeves 102 in any of a number of ways, for example, by pushing orpulling, so it can be driven into the arcuate through apertures 6 a. Thenitinol implant 160 a also can be inserted into the arcuate throughapertures 6 a in any of the other fashions described above in connectionwith FIGS. 5A-B.

[0094] Additionally, d sharp edge of the nitinol implant can be usedlike a reamer or awl to thereby enlarge the initial through hole 6 asthe implant is being inserted or driven into the initial thoughaperture. This avoids the intermediate step of drilling or otherwiseforming the arcuate through aperture 6 a before, insertion of theimplant.

[0095]FIG. 7C depicts an illustrative device 400 for inserting a nitinolimplant 160 a, which device includes a guide tube 402 and a pusher 404.The distal end 408 of the guide tube 402, similar to the positioning jigguide sleeve distal end 108 is preferably configured so as to be capableof releasably mating with a surface, or portion thereof, of thevertebrae 2 where the entrance of the arcuate through aperture 6 a islocated. In the illustrated embodiment, the guide tube distal end 408 isconfigured with a cut out so as to receive a corner of the vertebrae 2therein.

[0096] The distal end 408 is disposed on the vertebrae so that the lumentherein is aligned with the arcuate through aperture 6 a. Thestraightened nitinol implant 160 a is inserted into the guide tube 402along with the pusher 404 such that the distal end of the pusher is incontact with the proximal end of the nitinol implant. The pusher distalend 408 mates with the implant proximal end so as to maintain theorientation and direction of the nitinol implant 160 a within the guidetube 402 so that it curves in the proper direction when it exits theguide tube. Alternatively, and as shown in FIGS. 8A-B, the orientationof the nitinol implant 160 a within the guide tube 402 is maintainedwith a flat side or with a key and notch type of arrangement.

[0097] The pusher 404 includes a stop 406 to limit the travel of thepusher within the guide tube 402. This in turn limits the amount oftravel by the nitinol implant 160 a so as to assure that the implantremains buried within the vertebrae and not exposed above the surfacethereof.

[0098] The placement of the implant according to the systems and methodsof the present invention is advantageous in that the inserted implantresides completely within the vertebrae and, thus, within the spine,with no protrusion as compared with prior art devices. The implant andits placement provide a configuration which allows for some compressionand cantilever force, but deters rotation and sheer. Additionally, inthe present device, the moment arm is more centrally located within thespine as compared to prior devices. This central location also providesbetter stability in the face of torsion as compared to prior artdevices.

[0099] In general, the placement of an arcuate implant within thearcuate through apertures as described herein is particularlyadvantageous because the implant is buried to avoid contact withneurovascular structures. The placement provides load sharing and thusprovides a better healing bio-mechanical environment and also provides amore advantageous fixation to avoid mechanically sub-optimal stresses.Also important, this method allows securement and avoids displacement ofa spinal fusion or disk replacement device without modification ordamage to the vertebrae's load bearing surface. Rather, one or two holesplaced in or around the center of a vertebrae can be sufficient. Themethod and positioning jig 100 of the present invention also areadvantageous in that the jig can be adapted for use in minimallyinvasive procedures. Additionally, the capability to position implantsin accordance with the methods described herein enables avoiding bloodvessel injury, erosion into organs and damage to adjacent nerves. Thisprovides a significant advantage over presently existing technologiesfor disorders of the spine including fractures, arthritis, deformity,infections, tumor and mechanical spinal disorders.

[0100] Although the foregoing method describes extending a singleimplant between adjacent vertebrae this description should not beconstrued as being a limitation as one or more implants can bepositioned across each motion segment as described herein.

[0101] In addition, the above described method can be further adapted soas to be used to secure an intravertebral prosthetic device 500 (i.e.,artificial disc) such as that shown in FIG. 6A. According to this aspectof the invention, the implant is made partly or wholly from a flexiblematerial such as silicon, elastomeric, polymers, polyurethanes andcopolymers thereof, hydrogels, collagen, bioabsorbables, compositions,or a metallic spring or coil, so as to allow continual mobility betweentthe vertebral bodies. One or more arcuate implants are provided whichpass through a partial or complete hold in the prosthesis. Thiseffectively prevents the prosthesis from becoming dislodged as well asmaintaining its location and orientation within the disc space.

[0102]FIG. 9 shows a method for inserting an implant 600 according to asecond aspect of the present invention. A final through aperture 604 isformed in each of the vertebrae in accordance with above describedtechniques such as by drilling. Except that the through aperture 604that receives the implant can be straight as shown in FIG. 9 or can bearcuate as shown in any of FIGS. 3-6. As such, reference should be madeto the foregoing discussion for further details regarding the formationof the final through aperture 604.

[0103] In the method according to the second aspect, the implant is intwo sections 602 a,b. The proximal ends 608 of the two sections 602 a,bare particularly configured so they can be mated to each other andinterlocked to each other by means of an interference fit, a nut andbolt, a screw or a pin 606. Thus, to fix the moveable segment, onesection 602 a is inserted into the through aperture 604 in one vertebrae2 and the second section 602 b is inserted into the through aperture 604of the other vertebrae. The two sections 602 a,b are inserted into theirrespective through apertures until the proximal ends 608 thereof aremated to each other. The pin 606 or other securing mechanism is thenused to interlock the proxima ends and thus form a rigid implant.Although the sections are illustrated as being straight, it is withinthe scope of the present invention for the sections to arcuate so as toform an interlocking rod when assembled.

[0104]FIG. 10 shows a method for inserting an implant 600 according to athird aspect of the present invention. According to this method, theapertures 702 in each vertebrae. 2 are formed so they extend from thevertebral space 4 outwards, penetrating into the cancellous bone. Inthis aspect, the apertures 704 formed in the vertebrae need not bethrough apertures. The implant 600 is like that described above for thesecond aspect of the present invention except that it is inverted fromthat shown in FIG. 9.

[0105] There is respectively shown in FIGS. 11A,B a cutter bracketsystem 1100 and a curved bit or drill system 1120, the curved drillsystem being for use with such a cutter bracket system. The cutterbracket system 1100 and curved drill system 1120 comprises anotherembodiment of the present invention for forming arcuate apertures 6 a(FIG. 6A) in each of the adjacent vertebral bodies 2. Referring now toFIG. 11A, the cutter bracket system includes temporary vertebral screws1102, pivot brackets 1104 and a pivot arm 1106. In the illustratedembodiment, there is two temporary vertebral screws, 1102 that are eachsecured to the adjacent vertebral body 2 that is to be fused, however,this shall, not be construed as a limitation on the number ofintervertebral screws. Extending from the temporary vertebral screws1102 are the pivot brackets 1104, which locate the pivot point 1108 withrespect to the adjacent vertebral bodies 2 and maintain the pivot pointin this orientation. The pivot arm 1106 is rotatably mounted to thepivot brackets 1104 using any of a number of mechanisms or techniquesknown in the art so that the pivot arm pivots or rotates about the pivotpoint 1108. In an exemplary embodiment, the temporary vertebral screws1102, the pivot brackets 1104 and the pivot arm 1106 are e made fromstainless steel although other materials are contemplated.

[0106] The drill system illustrated in FIG. 11B includes a curvedcannula 1122, a flexible cable 1124, a cutting head or burr 1126 and amotor 1130. The flexible cable 1124 is rotatably disposed with thecurved cannula 1122. One end of the flexible cable 1124 is attached tothe cutting burr 1112 and the other end of the flexible cable 1124 isattached to the motor 1130, whereby the motor drives the cutting burr soit to rotates in the desired manner. In the illustrated embodiment, themotor 1130 also is mounted to an end of the curved cannula 1122. In anexemplary embodiment, the curved cannula 1122 is made from stainlesssteel and the flexible cable 1124 is a flexible, teflon coated stainlesssteel cable, the cutting burr 1126 is made from stainless steel,although it is within the scope of the present invention for othermaterials to be used.

[0107] The motor 1130 includes any of a number of devices known in theart that develop or provide a rotary output which can be used to rotatethe flexible cable 1124, such devices include, but are not limited toelectric or pneumatic drills, DC/AC electric motors, or, pneumatic airdriven rotary motors. It also is within the scope of the presentinvention for the drill system 1120 to further include a couplingmember, as is known in the art, that operably and rotatablyinterconnects the flexible cable 1124 and the motor 1130 such that themotor is located remote from the curved cannula 1122. In this way, anyof a number of rotary devices such as a drill, that are readilyavailable, can be adapted for use in the drill system 1120 of thepresent invention and interconnected to the flexible cable 1124 by meansof the coupling member.

[0108] The drill system 1120 is mounted or attached to the pivot arm1106, distal from the pivot point 1108, by means of a connector 1128 onthe curved cannula 1122. The connector 1128 and the correspondingfeature on the pivot arm 1106 comprises any of a number of mechanisms ordevices known in the art (e.g., clamp type mechanism) by which thecurved cannula can be removably secured to the pivot arm so there isessentially no relative movement therebetween. In a particularembodiment, the curved cannula 1122 is secured proximal to or at thedistal end of the pivot arm. In this way when the drill system 1120 issecured to the cutter bracket pivot arm 1106 and the cutter bracketpivot arm 1106 is rotated about the pivot point 1108, the pivot armguides the curved drill system, in particular the cutting burr 1126 on awell-defined circular path.

[0109] In use, the cutter bracket system 1110 is temporarily secured tothe adjacent vertebral bodies 2 to be fused by the temporary vertebralscrews 1102. In particular the cutter bracket system 1110 is secured tothe vertebral bodies 2 so that the pivot point 1108 is positioned so asto be spaced from a surface of the vertebral bodies and so as to bebetween the adjacent vertebral bodies, more particularly, at about themidpoint of the intervertebral space 4. After securing the cutterbracket system to the vertebral bodies the curved drill system 1120 ismounted to the pivot arm as described above.

[0110] The pivot arm 1106 is then rotated in one direction, for examplea clockwise direction, about the pivot point 1108. As the pivot arm 1106is rotated thereabout, the cutting burr 1126 is operated so the drillsystem 1120 drills an arcuate hole in the vertebral body 2 on one sideof the pivot point. The curved drill is then remounted so the cuttingburr 1126 is on the other side of the pivot point 1108 and the pivot armis rotated in a counter clockwise direction so the, drill system 1120drills an arcuate hole in the vertebral body 2 on the other side of thepivot point 1108. In an exemplary embodiment, the arcuate hole iscompletely formed when the pivot arm 1106 bottoms out or contacts thevertebrae being drilled. After forming the arcuate holes, the curveddrill system 1120 is dismounted from the pivot arm 1106 and the cutterbracket system 110 is disconnected from the adjacent vertebral bodies 2.In this way, two matched arcuate holes are formed in the adjacentvertebral bodies 2 that are sized and configured to receive an arcuate,implant being inserted therein Reference shall be made to the foregoingdiscussion for further details regarding such an arcuate implant orfixation member.

[0111] Although the foregoing describes the formation of the arcuateholes or apertures 6 a in the adjacent vertebral bodies 2 using a curveddrill system 1120 mounted to the pivot arm 1106, this shall not beconstrued as a limitation. As discussed hereinabove is within the scopeof the present invention for other devices, mechanism or techniques,such as the above-described ablation energy sources, to be adapted foruse with a rotating pivot arm 1106 to form the, through holes/apertures.As such these other devices, mechanisms or techniques are contemplatedfor use with the above described cutter bracket system.

[0112] In accordance to another method of the present invention, a slotis cut in each of the adjacent vertebral bodies and a biscuit implant isinserted into the slots so as to also bridge across the intervertebralspace 4. Preferably the slots are simultaneously cut in the vertebralbodies so a common channel is formed therein. In an example embodiment,and with reference to FIGS. 12A,B there is provided a cutting device1200 having a cutting implement, for example a circular blade 1206 thatis rotated by a motor (not shown). The cutting device 1200 also isconfigured so the blade 1206 is moveable between a first position, wherethe blade is disposed within the device housing 1202 (FIG. 12A), and asecond position where a portion of the blade extends outwardly apredetermined distance from an exterior side 1204 of the housing (FIG.12B). Preferably, the exterior side 1204 from which the blade 1206extends is configurable so that in one position the exterior side issubstantially parallel to a tangent at the midpoint of the blade andfurther includes indicia 1208 representative of the mid-point of theblade.

[0113] In use, and as shown in FIG. 12C the cutting, device 1200 ispositioned so the device housing exterior side 1204 abuts or is adjacentto the vertebral bodies 2 and so the indicia 1208 representative of theblade midpoint is pointing towards the intervertebral space 4,preferably about a midpoint between the adjacent vertebral bodies. Therotating circular blade 1206 is then moved from the first to the secondposition so as to simultaneously cut an arcuate slot in each of theadjacent vertebral bodies 2. After cutting the slot, the circular blade1206 is returned to the first position with the device housing 1202 andthe cutting device 1200 is removed from the vertebral bodies.

[0114] As shown in FIG. 12D, after the arcuate slot 1209 is cut in theadjacent vertebral bodies 2, a biscuit implant 1210 such as that shownin FIG. 12F, is inserted into the arcuate slot in each of the adjacentvertebral bodies and so as to bridge therebetween. The biscuit implant120 a is secured in the arcuate slot 1209 using any of the methodsdescribed herein for the other implants of the present invention therebyfusing and stabilizing the adjacent vertebral bodies. Alternatively, abiscuit implant 1210 b such as that shown in FIG. 12G, is configured soas to include a spacer element 1212. Thus, when the biscuit, implant1210 b is inserted into the arcuate slots 1209 the spacer element 1209thereof is received and disposed in the intervertebral space as shown inFIG. 12E.

[0115] In addition to the exemplary biscuits implants 1210 a,billustrated in FIGS. 12F-G it is with within the scope of the presentinvention for the biscuit implant whether it is configured with orwithout a spacer element 1212, to be formed in any of a number ofgeometric shapes that are otherwise consistent with the intended use.This includes the biscuit implants 1210 c-f shown in FIGS. 12H-K.Reference shall be made to the foregoing discussion regarding the otherimplants or fixation members of the present invention as to thematerials and other features (e.g., fenestartions) which apply equallyfor a biscuit implant according to the present invention.

[0116] There is shown in FIGS. 13A-13F, an implant-system according tothese systems and methods. FIG. 13A shows an embodiment of the innerimplant 800 adapted for inspection within the outer implant 810 shown inFIG. 13B. The inner implant 890 in FIG. 13A is shown as a substantiallyhollow device equipped with a fenestrated wall 802. The inner implant800, bears on a lateral surface 814 a key slat 804 adapted to secure andorient the inner implant 800 within the outer implant 810 shown in FIG.13B. Specifically, the key slat 804 in the illustrated embodiment canslide into a key groove 808 situated on the inner aspect 818 of theouter implant 810. In the embodiment shown in FIG. 5B, the outer implantis equipped with a trough and trough slit and a fenestrated wall 812 asshown in FIG. 13D. It is understood that the devices shown in thesefigures can be fabricated from a plurality of materials including bothabsorbable and non-absorbable biocompatible materials. Materials mayinclude metallics, ceramics, plastics, polymers, biological materialsand materials produced by biotechnology. A variety of suitable materialswill be readily envisioned by those of ordinary skill in the art for usein the system and methods of the present invention.

[0117]FIG. 13C shows a lateral view of two vertebral bodies 820 and 822showing the general position of the implant system 824. In more detail,the edge of the outer implant 828 is shown imbedded and buried in thevertebral bodies 820 and 822. The edge of the inner implant 830 is shownpositioned within the intervertebral disc space 834. A set of bone cuts832 and 836 are made at the buried end of the implant, system 824. FIG.13D shows an anterior view of the outer implant 838 positioned with theinner implant 840 secured within it according to the systems and methodsof the present invention. FIG. 13E shows an anterior view of the innerimplant 844 secured within the outer implant 842 according to thesystems and methods of the present invention. In FIG. 13E, however, theentire implant system 845 is shown in the rotated 90 degrees relative tothe angle at which the implant system 848 is inserted into the vertebralbodies and disc space (not shown). The inner implant 844 in this viewassumes a vertical position within the implant system 848, and the outerimplant is rotated 90 degrees to effect this repositioning.

[0118]FIG. 13F shows in more detail a perspective view of an embodimentof the implant system 850 according to the present invention. The innerimplant 854 is shown positioned within the outer implant 858, the entireimplant system 850 being turned vertically. As a consequence of thisrepositioning two bone sections 860 contained between the inner implant854 and the outer implant 858 are turned to a vertical position. Thesebone sections 860 thus provide structural stability to the system 850and to a spine unit (not shown). The vertical repositioning placescortical bone in a more supportive position.

[0119] In the illustrated embodiment, the outer implant 858 is shownwith a fenestrated wall 852 for facilitating bony ingrowth. Thesefenestrations are larger at the upper and lower confines of therepositioned bone graft sites to enhance fusion. Also in the illustratedembodiment, the inner implant 854 is shown with a hollow interiorsection 862 available for containing a solid displacing shim and bonechips, bone matrices, growth factors, or other agents for encouraging orfacilitating bony ingrowth and, enhancing stable positioning of theverticalized cortical bone sections. Other substances useful to thehealing process can be provided within this interior section 862. Forexample, antibiotics can be placed in this interior section 862 in asuitable vehicle. Other substances and matrices can be envisioned bypractitioners of those arts that will fall within the scope of thepresent invention.

[0120] In more specific embodiments, the outer implant 838,858 isconfigured so as to include an axially extending slot or slit 841,864that is arranged and configured so as to permit adjustment of thediameter of the outer implant, for example to permit the outer implantto be expanded outwardly. Thus, bone sections can be placed with astight a positioning as possible and the outer implant 838,858 can beplaced in firmer or closer engagement with the vertebral bodies 820,822.The structure forming the adjustment slit 841,864 includes any of anumber of configurations, structures or arrangements that permitrelative movement between the sides of the outer implant on either sideof the adjustment slit. Such structures, arrangements and configurationsinclude, but are not limited to an axially extending through aperture oran axially extending ship-lap type of joint where portions of theaxially extending sides slidably overlap each other.

[0121] There is generally down in FIGS. 14A-14C, an inner tool 900 to beused, according to the systems and methods of the present invention.FIG. 14A shows the inner tool 900 positioned with the intervertebraldisc space 906. The inner tool 900 bears on its distal end, a shorterdisc end 902 that is adapted for insertion within the intervertebraldisc space 906 to allow for cutting a segment of the vertebral bodies904 and 908 above and below it. FIG. 14B shows a perspective view of aninner tool 910 according to the systems and methods of the presentinvention. The distal end 912 thereof is adapted for cutting thecortical vertebral end plates that it abuts. FIG. 14C shows in moredetail an embodiment of the cutting mechanism bone by the inner tool916. A cutting end 914 at the distal end of the tool 916 bears a set ofstop cut blades shown here in the retracted position 920 and in theextended position 918. Directing the blades from the retracted position920 to the extended position 918 effects a cut in the adjacent bone(vertebral endplate, not shown). While the depicted embodiment of a toolcan be advantageously employed in conjunction with the implant systemaccording to these systems and methods other tools and, devices can beenvisioned by skilled practitioners of these arts for cutting bone andfor positioning an implant system all modification that fall within thescope of the present invention.

[0122]FIG. 15 shows a lateral view of an embodiment of the tool system1000 according to the present invention positioned in relation to thevertebral bodies 1014 and 1018. In this view an inner tool 1002 is shownwith its distal end positioned between the vertebral bodies 1014 and1018. An outer tool 1004 is shown in two positions, a position 1008before driving it into the vertebral bodies 1014 and 1018 and a position1020 after driving it into the vertebral bodies 1014 and 1018. A blade1022 of the outer tool 1004 is shown positioned at the anterior aspectof the vertebral body 1014 before the outer tool 1004 is driven into thevertebral body 1014. In this position 1020 after driving the tool 1004into the vertebral body 1018, the blade 1024 is shown imbedded in thevertebral body 1018, having cut it perpendicular to its anterior face.The inner tool 1002 can make bone cuts 1012 at right angles to the blade1024 of the outer tool 1004, thereby creating a bone slab 1010 that canbe repositioned according to the systems and methods of the presentinvention. This bone slab 1010 (section) can be cut so as to allow foranterior vertebral distraction by making these slabs oblong rather thancircular.

[0123] It should be clear that the methods, systems, and devices of theinvention are not limited to securing a pair of vertebrae, but ratherany combination of multiple vertebrae segments. It also should be clearthat the methods, systems, and devices are in no way limited tovertebrae segments. In particular, the invention enables securing anysolid substrates particularly bone substrates, without use of protrudingscrews or plates. In this regard, FIG. 16 shows a bone-to-boneapplication using techniques of the invention. It also should beunderstood that the invention is applicable to a wide variety offixation configurations, including bone-to-bone with a gap; bone-to-bonewithout a gap; bone-to-bone with bony spacers; and bone-to-bone with anon-bony spacer such as a metal, polymer, or a biodegradable maternal.

[0124] Although a preferred embodiment of the invention has beendescribed using specific terms, such description is for illustrativepurposes only, and it is to be understood that changes and variationsmay be made without departing from the spirit or scope of the followingclaims.

What is claimed is:
 1. A method for stabilizing adjacent vertebrae of aspine, comprising implanting an arcuate fixation member between thevertebrae.
 2. The method of claim 1 wherein the member is implantedthrough a preformed aperture in each of the adjacent vertebrae.
 3. Themethod of claim 1 wherein the preformed aperture hasp been drilled ineach of the adjacent vertebrae.
 4. The method of claim 1 whereinapparatus the fixation member is the sole apparatus employed to affixthe vertebrae.
 5. The method of claim 1 wherein the member is made fromone or more of a metal, bone, morphogenic protein, carbon fibercomposite, nitinol, a biodegradable material, collogen or collagencoated metal or bone.
 6. The method of claim 1 wherein the implant isone of solid, hollow or with ingrowth fenestrations and screw holes orexpansion bolts or staples.
 7. A method for stabilizing adjacentvertebrae of a spine, comprising: providing a positioning apparatusincluding two guide sleeves, each guide sleeve having a long axis;locating the two guide sleeves with respect to the adjacent vertebraesuch that a vertex formed by the long axis of each guide sleeve islocated in the intervertebral space for the adjacent vertebrae; formingan aperture in each of the adjacent vertebrae using the guide sleeves;and inserting an implant into the apertures formed in each of theadjacent vertebrae so that the implant extends between the adjacentvertebrae and through the intervertebral space.
 8. The stabilizingmethod of claim 7 wherein said step of forming includes forming anarcuate aperture in each of the adjacent vertebrae such that the arcuateapertures in the adjacent vertebrae have a common axis of rotation. 9.The stabilizing method of claim 7 wherein the step of forming includesforming an aperture in each of the adjacent vertebrae by one of drillingor ablation of the bone by an energy source.
 10. The stabilizing methodof claim 8 wherein the step of forming includes forming an aperture ineach of the adjacent vertebrae by one of drilling or ablation of thebone by an energy source.
 11. The stabilizing method of claim 8 whereinthe step of forming includes: drilling an initial aperture in each ofthe adjacent vertebrae so as to, create intersecting apertures withconvergent paths within the intervertebral space; and enlarging theinitial aperture so as to form the aperture that receives the implant.12. The stabilizing method of claim 11 wherein the step of enlargingincludes enlarging the initial aperture using one of a drill bit, areamer, an awl, coring device or energy source.
 13. The stabilizingmethod of claim 11 wherein the method of forming further includesinserting a drill bit into each of the guide sleeves for drilling of theinitial aperture.
 14. The stabilizing method of claim 1 wherein the stepof forming further includes; inserting a guide member, after drilling ofthe initial aperture, into one of the guide sleeves, down through theinitial aperture in one adjacent vertebrae, through the intervertebralspace and into the initial aperture in the other adjacent vertebrae; andadvancing an aperture-enlarging device over the guide member to enlargethe initial aperture.
 15. The stabilizing device of claim 14 wherein theaperture enlarging device is one of a curved reamer, curved drill bit orcoring device, and wherein said step of advancing includes advancing theone of the curved reamer, the curved drill bit or coring device over theguide member so as to form an arcuate aperture in each of the adjacentvertebrae.
 16. The stabilizing method of claim 7 wherein the step offorming includes, inserting a drill bit into each guide sleeve; drillingan initial aperture in each of the adjacent vertebrae so as to createintersecting apertures with convergent paths within the intervertebralspace; inserting a guide member, after drilling of the initial aperture,into one of the guide sleeves down through the initial aperture in oneadjacent vertebrae, through the intervertebral space and into theinitial aperture in the other adjacent vertebrae; and advancing anaperture-enlarging device over the guide member to enlarge the initialaperture to form the aperture that receives the implant.
 17. Thestabilizing method of claim, 16 wherein the aperture-enlarging device isone of a drill bit, a reamer, an awl or energy source.
 18. Thestabilizing method, of claim 16 wherein the aperture enlarging device isone of a curved reamer, a curved drill bit, a curved drill or an energysource, and wherein the step of advancing includes advancing the one ofthe curved reamer, the curved drill bit, the curved drill or the energysource over the guide member so as to form an arcuate aperture in eachof the adjacent vertebrae, the arcuate apertures in the adjacentvertebrae having a common axis of rotation.
 19. The stabilizing methodof claim 7 wherein the positioning apparatus being provided furtherincludes a cross member and an intervertebral spacer, where the guidesleeves are pivotally mounted to the cross member and the intervertebralspacer is spaced from the cross member and, interconnected thereto atabout a mid point between the pivots points for the guide sleeves; andwherein said stabilizing method further comprises: locating theintervertebral spacer in the intervertebral space between the adjacentvertebrae; and maintaining alignment of the guide sleeves with respectto the adjacent vertebrae so that a consistent angle is maintainedbetween the guide sleeve and the vertebrae during at least a portion ofsaid forming of the aperture.
 20. The stabilizing method of claim 11wherein the positioning apparatus being provided further includes anintervertebral spacer; said stabilizing method further comprises thestep of locating the intervertebral spacer in the intervertebral spacebetween the adjacent vertebrae; and wherein the intervertebral spacer isconfigured so as to provide protection to the spine during said drillingwhen disposed in the intervertebral space.
 21. The stabilizing method ofclaim 8 wherein the step of implanting includes successively drawing aportion of the implant through the arcuate aperture in one adjacentvertebrae, through the intervertebral space and into the arcuateaperture of the other adjacent vertebrae.
 22. The stabilizing method ofclaim 8 wherein the step of implanting includes: securing one end of aguide wire to an end of the implant; passing a free end of the guidewire through the arcuate aperture in one of the adjacent vertebrae,through the intervertebral space and through the arcuate aperture in theother adjacent vertebrae; and, pulling on the guide wire free end tothereby successively draw the portion of the implant.
 23. Thestabilizing method of claim 8 wherein the step of implanting includes:inserting, a beginning end of the implant into an entrance opening ofone of the adjacent vertebrae; applying a force to the portion of theimplant extending from the entrance opening so as to drive the implantbeginning end though the arcuate aperture in the aperture of said one ofthe adjacent vertebrae, through the intervertebral space and into thearcuate aperture in the other of the adjacent vertebrae.
 24. Thestabilizing method of claim 8 wherein the method further comprises:inserting a beginning end of the implant into an entrance opening of oneof the adjacent vertebrae; and applying a force generated by a forcegenerating mechanism to the portion of the implant extending from the,entrance so as to drive the implant beginning end though the arcuateaperture in the aperture of said one of the adjacent vertebrae, throughthe intervertebral space and into the arcuate aperture in the other ofthe adjacent vertebrae.
 25. The stabilizing method of claim 24 whereinthe method further comprises: locating an intervertebral spacer in theintervertebral space between the adjacent vertebrae; and attaching theforce generating mechanism to the intervertebral spacer.
 26. Thestabilizing method of claim 7 wherein the implant is made from one ormore of a metal, bone, morphogenic protein, carbon fiber composite,nitinol or a biodegradable material.
 27. The stabilizing method of claim7 wherein the implant is one of solid, hollow or with ingrowthfenestrations.
 28. The stabilizing method of claim 7 wherein one end ofeach guide sleeve, the end which contacts a surface of the adjacentvertebrae is configured to accept a surface feature of the adjacentvertebrae surface and includes surface artifacts that mechanicallyengage the adjacent vertebrae.
 29. The stabilizing method of claim 7wherein the implant includes a first and a second section and a distalend of each of the first and second sections being configured so as tobe capable of being secured together, and wherein the method furthercomprises: inserting the implant, first section into the aperture in oneof the adjacent vertebrae so that the distal end therefore is disposedin the intervertebral space; inserting the implant second section intothe aperture in one of the adjacent vertebrae so that the distal endtherefore is disposed in the intervertebral space; securing the distalends of the first and second sections together.
 30. The stabilizingmethod of claim 29 wherein the apertures in the adjacent vertebrae arearcuate and wherein the implant first and second sections are arcuatehaving a radius substantially the same as that for the arcuateapertures.
 31. The stabilizing method of claim 29 wherein a long axisfor each of the first and second sections is substantially straight. 32.The stabilizing method of claim 7 further comprising the step ofsecuring a portion of the implant proximal the ends thereof to theadjacent vertebrae.
 33. The stabilizing method of claim 29 wherein thestep of securing the distal ends includes securing the distal ends byone of a nut, bolt, pin, stable, or expansion bolt.
 34. An implantablespinal fixation system, comprising: an arcuate implant member of a sizesufficient to extend between two adjacent vertebrate.
 35. The system ofclaim 34 wherein the implant member is constructed of one or more of ametal, bone, morphogenic protein, carbon fiber composite, nitinol or abiodegradable material.
 36. A spinal system comprising: a mammalianspine with a surgically implanted arcuate member extending between twoadjacent vertebrae.
 37. The system of claim 36 wherein the arcuatemember is constructed of one or more of a metal, bone, morphogenicprotein, carbon fiber composite, nitinol or a biodegradable material.38. A spinal fusion kit comprising an arcuate fixation member.
 39. Aspinal fixation kit comprising a positioning apparatus including: twoguide sleeves, each guide sleeve having a long axis, a cross member, anintravertebral spacer, wherein the guide sleeves are pivotably mountedto the cross member, and wherein the intravertebral spacer is spacedfrom the cross member and interconnected thereto so as to be between thepivots points for the guide sleeves; and a fixation member.
 40. Thespinal fixation kit of 39, wherein the fixation member is arcuate. 41.The spinal fixation kit of claim 40, wherein the fixation member is oneof a solid or hollow member.
 42. The spinal fixation kit of claim 40,wherein the fixation member is configured with at least onefenestration.
 43. The spinal fixation kit of claim 39, wherein thefixation member includes a first section and a second section, a distalend of each of the first and second sections being configured so as tobe capable of being secured together thereat; and a mechanism thatsecures the distal ends of the first and second sections together. 44.The spinal fixation kit of claim 39, further comprising a guide wire, anend of the guide wire being configured to be interconnected to one endof the fixation member, and the guide wire being used to implant thefixation member in adjacent vertebrae.
 45. The spinal fixation kit ofclaim 39, wherein the fixation member is made from one of a metal, bone,bone with bone morphogenic protein, carbon fiber composite, nitinol or abiodegradable material.
 46. The spinal fixation kit of claim 39, furthercomprising a force generating device used to apply a force to thefixation member for implanting the fixation member in adjacentvertebrae.
 47. A method for fixing two adjacent vertebrae to facilitatea bony union thereof, comprising: performing a diskectomy of anintervertebral space; transecting a segment of bone from a surface of avetrebra bordering the intervertebral space; freeing the segment of bonefrom the surface of the vertebra from a horizontal to a vertical plane;securing the segment of bone in the vertical plane to span theintervertebral space; thereby fixing two adjacent vertebrae tofacilitate a bony union thereof.
 48. A method for stabilizing, adjacentvertebrae of a spine, comprising: providing a positioning apparatusincluding a pivot arm that is rotatable about a pivot point; locatingthe positioning apparatus with respect to the adjacent vertebrae suchthat the pivot point is disposed between the adjacent vertebrae; formingan aperture in each of the adjacent vertebrae responsive to rotation ofthe pivot arm about the pivot point; and inserting an implant into theapertures formed in each of the adjacent vertebrae so that the implantextends between the adjacent vertebrae and through the intervertebralspace.
 49. The stabilizing method of claim 48 wherein said step offorming includes forming an arcuate aperture in each of the adjacentvertebrae.
 50. The stabilizing method of claim 48 wherein the step offorming includes forming an aperture in each of the adjacent vertebraeby one of drilling or ablation of the bone by an energy source.
 51. Thestabilizing method of claim 48 wherein the step of locating includeslocating the pivot point such that it is spaced from a surface of theadjacent vertebrae and disposed at a point between the adjacentvertebrae.
 52. The stabilizing method of claim 48 wherein the apparatusbeing provided further includes a drill that is affixed to the pivot armsuch that when the pivot arm rotates about the pivot point the drillfollows a defined arcuate cutting path.
 53. The stabilizing method ofclaim 52 wherein the drill includes a curved drilling element.
 54. Thestabilizing method of claim 48 wherein the positioning apparatus furtherincludes a frame to which the pivot arm is rotatably mounted and whereinthe step of positioning includes securing the frame to the adjacentvertebrae so the pivot point is located at the desired position.
 55. Thestabilizing method of claim 51 wherein the pivot point is locatedopposite the intervetebral space.
 56. The stabilizing method of claim 53wherein the curved drilling element comprises a curved cannula, aflexible member disposed within the curved cannula, and a cutting burraffixed to an end of the flexible member, the flexible burr for cuttingan arcuate aperture in each of the adjacent vertebrae.
 57. Thestabilizing method of claim 52 wherein the step of forming includesrotating the pivot arm in one direction to form the aperture in one ofthe adjacent vertebrae and rotating the pivot arm in an oppositedirection so as to form the aperture in the other of the adjacentvertebrae.
 58. The stabilizing method of claim 57 wherein the apparatusbeing provided further includes a drill that is affixed to the pivot armsuch that when the pivot arm rotates about the pivot point the drillfollows a defined arcuate cutting path, and wherein said step of formingfurther includes remounting the drill on the pivot arm prior to saidrotating the pivot arm in the opposite direction so that the drill ispositioned for forming the aperture in said other of the adjacentvertebrae.
 59. The stabilizing method of claim 57 wherein the drill is acurved drill.
 60. A method for stabilizing adjacent vertebrae of aspine, comprising: providing a cutting device including a cuttingimplement having midpoint; positioning the cutting device proximal asurface of the adjacent vertebrae and so that the cutting implementmidpoint is located between the adjacent vertebrae; cutting a commonchannel in the adjacent vertebrae with the cutting implement; andinserting a biscuit implant into the common channel so that the implantextends between the adjacent vertebrae and through the intervertebralspace, the space between the adjacent vertebrae.
 61. The stabilizingmethod of claim 60 wherein the cutting device being provided isconfigured such that the cutting implement is moveable between a firstposition in which the cutting implement is disposed within the cuttingdevice and a second position in which a portion of the cutting implementextends outside of the cutting device and wherein the step of cuttingincludes moving the cutting implement to the second position to cut thecommon channel in the adjacent vertebrae.
 62. The stabilizing method ofclaim 60 wherein the biscuit implant includes a spacer element andwherein the step of inserting includes inserting the biscuit implantinto the common, channel, such that the spacer element is disposed inthe intervertebral space.
 63. The stabilizing method of claim 60 whereinthe step of positioning includes positioning the cutting device so thecutting implement midpoint is located at the midpoint between theadjacent vertebrae
 64. A spinal fixation kit comprising a cutter bracketsub-system and a fixation member, wherein the cutter bracket sub-systemincludes: a frame being configured so as to be removably securable toadjacent vertebrae; and a pivot arm rotatably mounted to the frame. 65.The spinal fixation kit of claim 64 further comprising one of a drill oran ablation energy source.
 66. The spinal fixation kit of claim 64further includes a drill and wherein the pivot arm and the drill areconfigured so the drill is removably secured to the pivot arm.
 67. Thespinal fixation kit of claim 66 wherein the drill includes a curveddrilling element.
 68. The spinal fixation kit of claim 67 wherein thecurved drilling element includes a curved cannula, a flexible memberdisposed within the curved cannula, and a cutting burr affixed to an endof the flexible member, the flexible burr being configured for cuttingan arcuate aperture in a vertebrae.
 69. A spinal fixation kit comprisinga cutting device and a fixation member, wherein the cutting deviceincludes a cutting element that is moveable from a first position inwhich the cutting element is disposed within a housing of the device anda second position in which a portion of the cutting element is disposedoutside of the device housing.
 70. The spinal fixation kit of claim 69wherein the cutting element is a circular blade.
 71. The spinal fixationkit of claim 70 wherein the fixation member is a biscuit implantconfigured to complement the shape formed by the cutting circular blade.72. The spinal fixation kit of claim 70 wherein the fixation memberincludes a spacer element configured so as to be capable of beingreceived in an intervertebral space between adjacent vertebrae.